Process for cracking hydrocarbon oils



G. EGLOFF ET AL PROCESS FOR CRACKING HYDROCARBON OILS Nov. 24, 1931.

Original Filed July 6 Patented Nov. 24, 1931 UNITED STATES PATENT OFFICEGUSTAV EG-LOFF AND HARRY P. BENWER, OF CHICAGO, ILLINOIS, ASSIGN'ORS 'IO UNI- V'ERSAI OIL PRODUCTS COMPANY, OF CHICAGO, ILLINOIS, CORPORATIONOF SOUTH DAKOTA PROCESS FOR CRACKING HYDROCAIRZ BON OILS Originalapplication filed July 6, 1920, Serial No. 394,083. Divided and thisapplication filed August 26,

- 1921. Serial No. 495,573.

are to provide a process of thermal and pressure distillation of heavyhydrocarbon oils to produce light oil therefrom by means of a doublepressure still, a carbon settling tank and spraying oil over-the surfaceof the oil is in the up er still of the double pressure stills to provie a process ofproducing light oils from heavy oils by means of pressuredistillation in a double pressure still while pumping raw oil into thelower still of the double pressure still; to provide a process ofthermal and pressure distillation of hydrocarbon oils to producegasoline or other light oils therefrom by means of mixing the relativelycool dephlegmated oil with raw oil and pumping same to the bottom of thelower still of the double pressure stills; to provide a process ofpressure distillation in which the carbon and heavy oil from the lowerpressure still are drawn into a settling tank having baffle platestherein to settle out the carbon and draw the carbon free oil by meansof a pump and spraying said oil upon the liquid of the upper still ofthe double pressure stills; and, in general, to provide an improvedprocess of the character referred to.

In the drawingnthe single figure illustrates a view partly in sideelevation and partly in vertical section of our novel form of apparatusused in carrying out our process.

Referring to the drawing-1 designates a gas burner, 2 the furnaceprovided with a bridge wall 2a and stack 27). In the furnace is mountedthe still which. as shown, may consist of a pair of cylindrical shells 3and 4. the former mounted below and the latter above bridge well 2a.These shells 3 and 4 are connected by means of the pipes or conduits 5,the upper ends of which preferably project above the bottom of the shell4. To the upper end of the shell 4 is connected a goose-neck or vaporline 6 which is connected by pipe 7 to a dephlegmator 7a. Thisdephlegmator 7a consists of the cross headers 77 and 70 connected byright angle pipes 7d. The vapors pass from the dephlegmator 7a Chargingstock or fresh oil is fed to the shell 3 from charging line 18 connectedto pump 20 leading to any suitable source of supply. A valve 21 may beinterposed in the charging line, if desired. The reflux condensate whichfalls back from dephlegmator 7 a passes through pipe 7 into branch 22which is connected as shown at 23 to charging line 18. It is to be notedthat line 22 is of larger diameter than charging line 18 for the reasonthat there is more reflux condensate than fresh oil normally fed intothe still. In other words, this difi'erential capacity of the line 22and the charging line 18 causes the process to be carried out so as tomaintain the rate of condensation in said reflux condenser such that theamount of condensate formed per unit of time will be greater than theamount of raw charging oil supplied to the heating zone for the sameperiod, and consequently maintain a greater proportion of refluxcondensate than raw charging oil in the mixture supplied to the heatingzone. The feed line 24 is preferably somewhat larger than the line 22.The vapors which are generated in shell 3 pass up through pipes 5 intothe upper portion of the still or in other words the shell 4. Preferablythe shell 3 is normally kept three quarters full of liquid. The vaporswhich pass to the upper shell 4 will be subjected to a s'uperheatingaction. Oil is continuously drawn off through line 20a controlled byvalve 20?) into the bottom of the carbon settling tank 21a. i This tank21a is providedwit-h baffles 22a and 230 which tend to cause the carbonto precipitate out into the bottom of this tank. This carbon settlingtank is provided with manhole plate (not shown) so that it can bereadily cleaned out. The heavier oil containing a maximum amount ofcarbon is drawn off through line 25 controlled by valve 26. The cleaneroil passes through line 24a controlled by valve 27 to pump 28 whence itis returned by line 29 into the upper end of the shell 4. This line 29terminates in a perforated pipe 30 extending horizontally through theshell 4. A valve 31 is preferably interposed in line 29. The hot oilwhich passes through the perforated pipe 30 is in part vaporized and theunvaporized portioncan pass out through pipesbinto the shell 3 flowingcounter-current to the ascending vapors. The lines 22, 24, 20a, settlingtank 21a, pipe 24a and pipe 29 are preferably lagged or insulated so asto prevent as far as possible any reduction in temperature of the oilpassing therethrough.

The following description of the operation of the process may be given.The shell 3 is charged and kept charged to approximately 75% of itscapacity with, say, a. mid-continent gas oil of 32 Baum gravity. The oiltemperature in the shell 3 may be 750 F.

while the vapors that pass to shell 4 may be subjected to a vaportemperature of 820 F. A pressure of 105 pounds may be maintained on theentire system by suitably regulating the valves in the receiver 10 andthe residuum draw-off valve 26. If desired, a differential pressure maybe maintained by regulating the valve 32 interposed between line 9a. anddephlegmat-or 7 a. By regulating this valve 32 a pressure of 100 poundsmay be maintained on the still and dephlegmator and a pressure of 50pounds on the water condenser and receiver or atmospheric pressure onthe latter. These shells 3 and 4 may each be of 6 diameter and 30' longwith the rest of the apparatus approximately the proportionate sizeshown in the drawing. By means of this process, 65% of the gas oil maybe converted into pressure distillate having a gravity of 51 Baum andupon the basis of raw oil treated 36% of oil may be thus converted into58 Baum gravity gasoline.

The following modification of the process may be described. Instead offilling the shell still 3 three quarters full of oil, the oil may be fedin sufllcieut quantity into the still so as to maintain a liquid levelof approximate ly of the total capacity of the entire still. In otherwords, the liquid level of the oil will be maintained in shell lslightly below the perforated pipe 30.

In certain cases it may be desirable to carry out the modified processas, for example, in refractory oils difficult to crack, such as PineIsland gas oil, kerosene, steam still bottoms or Mexican gas oil, it isadvisable to have a maximum heating area per gallon of oil treatedcompared to dephlegmation surface. There are some easily cracked oilssuch as heavy asphaltie of the type of Iol'a crude, fuel oil fromwayside fields of Kansas, residuums or the like which require much lessradiating surface in relationship to heating surface for equivalentproduction of results from said hydrocarbon oils.

With reference to the novel form of appa ratus it is to be noted thatthe double pressure still shown permits of the use of smaller unitswhich have a much greater factor of safety than a single shell of thesame capacity. In addition, a maximum heating area is obtained for agiven capacity and also by means of this apparatus the vapors can bereadily superheated.

We claim as our invention 1. A process for cracking hydrocarbon oilsconsisting in maintaining a body of oil at a cracking temperature takingoff vapors therefrom, superheating said vapors, drawing off liquidresidue from said body, passing said liquid residue through a carbonsettling chamber, removing the cleaner portion of said oil from saidcarbon settling chamber and returning it directly to that portion of theapparatus in which the vapors are superheated.

2. A process for cracking hydrocarbon oils consisting in heating the oilto a cracking temperature, superheating the vapors in a secondary zoneconnected therewith, refluxing and condensing the vapors released fromthe secondary stage, removing the unvaporized oil from the initialheating stage, settling out the heavier end and returning the lighterends in an individual stream to the superheating stage.

3. A process for cracking hydrocarbon oils consisting in passing the oilto an initial cracking zone and heating the same therein to a.vaporizingand cracking temperature, superheating resultant vapors in a secondaryzone connected with said initial cracking zone, refluxing and condensingthe vapors released from the secondary zone, removing the unvaporizedoil from the initial cracking zone, settling out the heavier end of theunvaporized oil and passing the lighter ends thereof to the secondaryzone and there introducing them in dispersed form while maintaining aregulated vapor pressure upon the system during operation.

4. A process for cracking hydrocarbon oils, consisting in introducing abulk supply of oil to a cracking still disposed within a furnace wheresaid oil is subjected to a cracking temperature, in superheating thevapors from said oil by passing said vapors to a superheating drumlocated adjacent said cracking zone,

in discharging vapors from the drum to a reflux condenser, in passingthe uncondensed vapors to a final condenser, in returning refluxcondensate to said cracking still, and in continuously withdrawingresiduum from said cracking still, in removing carbon therefrom, and inintroducing the clean residual 011 to said superheating drum.

5. A process for cracking hydrocarbon oil, consisting in subjecting theoil to a cracking temperature'in a heating zone to cause substantialvaporization thereof, in superheating the vapors evolved from the oil bypassing the vapors through a su erheating drum, in discharging thevapors mm the drum to a reflux condenser, in continuously supplyingcharging oil mixed with reflux condensate to said heating zone, inmaintaining the rate of condensation in saidreflux condenser such thatthe amount of condensate formed per unit of time will be greater thanthe amount of raw charging oil supplied to the heating zone for the sameperiod, to thereby maintain a greater proportion of reflux condensatethan raw charging oil in the mixture supplied to the heating zone.

.6. A process for cracking hydrocarbon oil comprising maintaining aquantity of the hydrocarbon oil in a cracking zone under crackingconditions, removing residual hydrocarbons from said zone, separatingthe lighter from the heavier constituents of said residual hydrocarbons,passing said lighter constituents to a second zone wherein they areagain subjected to cracking conditions,

and admitting vapors from said first zone to said second zone.

' GUSTAV EGLOFF.

HARRY P. BENNER.

